Do you know where your fillers go? An ultrastructural investigation of the lips

Aim: To investigate the exact location and position of hyaluronic acid fillers in the perioral region by ultrasound and optical coherence tomography. Introduction: To date, there are few in vivo investigations in humans on the exact positioning of injectable hyaluronic acid fillers, and severe complications such as hematoma and thromboembolism are rarely addressed. Materials and methods: There were nine female patients investigated in this pilot study. All of them were periorally injected with hyaluronic acid. The exact product, amount, and locations, as well as the injection techniques, were recorded and compared. Before, immediately after, and 18 days after injection, photo documentation as well as high- resolution ultrasonography and optical coherence tomography of the lip surface were performed. Results: Minor bruising occurred, which resolved within 7 to 9 days. On day 18, no more hemorrhage could be detected. Injected material distributed well in the tissue, and no embolism or thrombosis occurred. However, the injected material came close (up to 1 mm) to important structures such as blood vessels. Lip wrinkles improved, and the lip surface was smoother and more even. Conclusion: Hyaluronic acid injections can improve aesthetics and reduce fine wrinkles of the lips. In the patients investigated in this study, compression of structures such as vessels and nerve fibers did not occur, nor did any severe complications result from injection. However, one must be aware of serious complications (eg, hematoma, thromboembolism) and the important anatomic structures (eg, orbicularis oris muscle, vessels, and nerves), and injecting physicians should always have hyaluronidase as a rescue medication at hand. Summary: Hyaluronic acid is a suitable tool for lip augmentation and reduction of fine lines; however, one must be aware of anatomic structures when injecting filler material into the lips and perioral area, and be familiar with the injection techniques.